Solid-state imaging device, method of manufacturing a solid-state imaging device, and electronic apparatus

ABSTRACT

Disclosed is a solid-state imaging device including a plurality of pixels and a plurality of on-chip lenses. The plurality of pixels are arranged in a matrix pattern. Each of the pixels has a photoelectric conversion portion configured to photoelectrically convert light incident from a rear surface side of a semiconductor substrate. The plurality of on-chip lenses are arranged for every other pixel. The on-chip lenses are larger in size than the pixels. Each of color filters at the pixels where the on-chip lenses are present has a cross-sectional shape whose upper side close to the on-chip lens is the same in width as the on-chip lens and whose lower side close to the photoelectric conversion portion is shorter than the upper side.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/490,350, filed Sep. 18, 2014, which claims priority to JapanesePatent Application No. JP 2013-197873, filed Sep. 25, 2013, the entiredisclosures of which are hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates to solid-state imaging devices, methodsof manufacturing the solid-state imaging devices, and electronicapparatuses and, in particular, to a solid-state imaging device, amethod of manufacturing the solid-state imaging device, and anelectronic apparatus capable of preventing the degradation of colormixture.

In recent years, CMOS type solid-state imaging devices (CMOS imagesensors) have been installed in various electronic apparatuses such asdigital cameras, video cameras, monitoring cameras, copiers, andfacsimile machines.

In solid-state imaging devices, on-chip lenses are formed overphotodiodes serving as light receiving portions. However, themanufacturing of the on-chip lenses with a desired curvature has becomedifficult since it is requested to downsize the on-chip lenses to suitto finer pixels.

Accordingly, there has been proposed the technology of achieving animprovement in sensitivity in a pixel structure in which on-chip lenseslarger in size than pixels are formed for every other pixel to suit tofiner pixels (see, for example, Japanese Patent Application Laid-openNo. 2007-287891 (hereinafter, referred to as Patent Document 1).

SUMMARY

Since the pixel structure disclosed in Patent Document 1 is the pixelstructure of a surface irradiation type, it is desired that the pixelstructure be applied to a rear surface irradiation type to furtherimprove sensitivity. However, the application of the pixel structuredisclosed in Patent Document 1 to the rear surface irradiation type maycause the degradation of color mixture.

The present disclosure has been made in view of the above circumstances,and it is therefore desirable to prevent the degradation of colormixture in the pixel structure of the rear surface irradiation type inwhich on-chip lenses larger in size than pixels are formed for everyother pixel.

A first embodiment of the present disclosure provides a solid-stateimaging device including a plurality of pixels and a plurality ofon-chip lenses. The plurality of pixels are arranged in a matrixpattern. Each of the pixels has a photoelectric conversion portionconfigured to photoelectrically convert light incident from a rearsurface side of a semiconductor substrate. The plurality of on-chiplenses are arranged for every other pixel. The on-chip lenses are largerin size than the pixels. Each of color filters at the pixels where theon-chip lenses are present has a cross-sectional shape whose upper sideclose to the on-chip lens is the same in width as the on-chip lens andwhose lower side close to the photoelectric conversion portion isshorter than the upper side.

A second embodiment of the present disclosure provides a method ofmanufacturing a solid-state imaging device having a plurality of pixelsand a plurality of on-chip lenses. The plurality of pixels are arrangedin a matrix pattern. Each of the pixels has a photoelectric conversionportion configured to photoelectrically convert light incident from arear surface side of a semiconductor substrate. The plurality of on-chiplenses are arranged for every other pixel. The on-chip lenses are largerin size than the pixels. The method includes forming each of colorfilters at the pixels where the on-chip lenses are present such that thecolor filter has a cross-sectional shape whose upper side close to theon-chip lens is the same in width as the on-chip lens and whose lowerside close to the photoelectric conversion portion is shorter than theupper side.

A third embodiment of the present disclosure provides an electronicapparatus including a solid-state imaging device. The solid-stateimaging device includes a plurality of pixels and a plurality of on-chiplenses. The plurality of pixels are arranged in a matrix pattern. Eachof the pixels has a photoelectric conversion portions configured tophotoelectrically convert light incident from a rear surface side of asemiconductor substrate. The plurality of on-chip lenses are arrangedfor every other pixel. The on-chip lenses are larger in size than thepixels. Each of color filters at the pixels where the on-chip lenses arepresent has a cross-sectional shape whose upper side close to theon-chip lens is the same in width as the on-chip lens and whose lowerside close to the photoelectric conversion portion is shorter than theupper side.

In the first and third embodiments of the present disclosure, theplurality of pixels each having the photoelectric conversion portionconfigured to photoelectrically convert light incident from the rearsurface side of the semiconductor substrate are arranged in a matrixpattern, the plurality of on-chip lenses larger in size than the pixelsare arranged for every other pixel, and each of the color filters at thepixels where the on-chip lenses are present has the cross-sectionalshape whose upper side close to the on-chip lens is the same in width asthe on-chip lens and whose lower side close to the photoelectricconversion portion is shorter than the upper side.

In the second embodiment of the present disclosure, each of the colorfilters at the pixels where the on-chip lenses are present is formedsuch that the color filter has the cross-sectional shape whose upperside close to the on-chip lens is the same in width as the on-chip lensand whose lower side close to the photoelectric conversion portion isshorter than the upper side in the solid-state imaging device includingthe plurality of pixels arranged in a matrix pattern, each of the pixelshaving the photoelectric conversion portion configured tophotoelectrically convert light incident from the rear surface side ofthe semiconductor substrate, and the plurality of on-chip lensesarranged for every other pixel, the on-chip lenses being larger in sizethan the pixels.

The solid-state imaging device and the electronic apparatus may beindependent apparatuses or modules incorporated in other apparatuses.

According to the first and third embodiments of the present disclosure,it is possible to prevent the degradation of color mixture.

Note that the effect of the present disclosure is not limited to the onedescribed above, but any of effects described in the present disclosuremay be produced.

These and other objects, features and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing the schematic configuration of a solid-stateimaging device according to an embodiment of the present disclosure;

FIG. 2 is a view showing a circuit configuration example of pixels;

FIG. 3 is a cross-sectional configuration view according to a firstembodiment of the pixels;

FIGS. 4A to 4C are a plan view and cross-sectional views of the pixelsaccording to the first embodiment;

FIG. 5 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 6 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 7 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 8 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 9 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 10 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 11 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 12 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 13 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 14 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 15 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 16 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 17 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 18 is a view for describing the method of manufacturing the pixelsaccording to the first embodiment;

FIG. 19 is a cross-sectional configuration view according to a secondembodiment of the pixels;

FIG. 20 is a cross-sectional configuration view according to a thirdembodiment of the pixels;

FIG. 21 is a cross-sectional configuration view according to a fourthembodiment of the pixels;

FIG. 22 is a cross-sectional configuration view according to a fifthembodiment of the pixels;

FIG. 23 is a cross-sectional configuration view according to a sixthembodiment of the pixels;

FIG. 24 is a view showing another arrangement example of color filters;

FIG. 25 is a view showing another arrangement example of the colorfilters;

FIG. 26 is a view showing another arrangement example of the colorfilters;

FIG. 27 is a view showing another arrangement example of the colorfilters;

FIG. 28 is a view for describing problems to be solved by the technologyof the present disclosure;

FIG. 29 is a cross-sectional configuration view according to a seventhembodiment of the pixels;

FIG. 30 is a view for describing the effect of the pixels according tothe seventh embodiment;

FIG. 31 is a cross-sectional view showing a modified example of theseventh embodiment of the pixels;

FIGS. 32A to 32D are views for describing a first method ofmanufacturing the pixels according to the seventh embodiment;

FIGS. 33A to 33D are views for describing the first method ofmanufacturing the pixels according to the seventh embodiment;

FIGS. 34A to 34D are views for describing a second method ofmanufacturing the pixels according to the seventh embodiment;

FIGS. 35A to 35D are views for describing the second method ofmanufacturing the pixels according to the seventh embodiment;

FIG. 36 is a cross-sectional configuration view according to an eighthembodiment of the pixels;

FIG. 37 is a view for describing the effect of the pixels according tothe eighth embodiment;

FIGS. 38A to 38D are views for describing the method of manufacturingthe pixels according to the eighth embodiment;

FIGS. 39A to 39D are views for describing the method of manufacturingthe pixels according to the eighth embodiment;

FIG. 40 is a cross-sectional configuration view according to a ninthembodiment of the pixels;

FIG. 41 is a cross-sectional configuration view according to a tenthembodiment of the pixels;

FIG. 42 is a cross-sectional configuration view according to an eleventhembodiment of the pixels;

FIG. 43 is a cross-sectional configuration view according to a twelfthembodiment of the pixels;

FIG. 44 is a cross-sectional configuration view according to athirteenth embodiment of the pixels;

FIG. 45 is a view for describing an effect according to the thirteenthembodiment;

FIG. 46 is a view for describing the optimum value of the superimposedamount of the color filters;

FIGS. 47A to 47D are views for describing the method of manufacturingthe pixels according to the thirteenth embodiment;

FIGS. 48A to 48D are views for describing the method of manufacturingthe pixels according to the thirteenth embodiment;

FIG. 49 is a cross-sectional configuration view according to afourteenth embodiment of the pixels;

FIGS. 50A to 50E are views for describing the method of manufacturingthe pixels according to the fourteenth embodiment;

FIGS. 51A to 51D are views for describing the method of manufacturingthe pixels according to the fourteenth embodiment;

FIG. 52 is a cross-sectional configuration view according to a fifteenthembodiment of the pixels; and

FIG. 53 is a block diagram showing a configuration example of an imagingapparatus serving as an electronic apparatus according to an embodimentof the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, modes (hereinafter referred to as embodiments) for carryingout the technology of the present disclosure will be described. Notethat the description will be given in the following order.

1. Schematic Configuration Example of Solid-State Imaging Device 2.Circuit Configuration Example of Pixels 3. First Embodiment of Pixels 4.Method of Manufacturing Pixels According to First Embodiment 5. SecondEmbodiment of Pixels 6. Third Embodiment of Pixels 7. Fourth Embodimentof Pixels 8. Fifth Embodiment of Pixels 9. Sixth Embodiment of Pixels10. Other Arrangement Examples of Color Filters 11. Seventh Embodimentof Pixels 12. First Method of Manufacturing Pixels According to SeventhEmbodiment 13. Second Method of Manufacturing Pixels According toSeventh Embodiment 14. Eighth Embodiment of Pixels 15. Method ofManufacturing Pixels According to Eighth Embodiment 16. Ninth Embodimentof Pixels 17. Tenth Embodiment of Pixels 18. Eleventh Embodiment ofPixels 19. Twelfth Embodiment of Pixels 20. Thirteenth Embodiment ofPixels 21. Method of Manufacturing Pixels According to ThirteenthEmbodiment 22. Fourteenth Embodiment of Pixels 23. Method ofManufacturing Pixels According to Fourteenth Embodiment 24. FifteenthEmbodiment of Pixels 25. Application Example to Electronic Apparatuses

1. Schematic Configuration Example of Solid-State Imaging Device

FIG. 1 shows the schematic configuration of a solid-state imaging deviceaccording to an embodiment of the present disclosure.

The solid-state imaging device 1 of FIG. 1 has a semiconductor substrate12 using, for example, silicon (Si) as a semiconductor. Thesemiconductor substrate 12 has a pixel array unit 3 in which a pluralityof pixels 2 are arranged in a matrix pattern and peripheral circuitunits on the periphery of the pixel array unit 3. The peripheral circuitunits have a vertical drive circuit 4, column signal processing circuits5, a horizontal drive circuit 6, an output circuit 7, a control circuit8, and the like.

Each of the pixels 2 has a photodiode serving as a photoelectricconversion element and a plurality of pixel transistors. The pluralityof transistors are composed of four MOS transistors, for example, atransfer transistor, a selection transistor, a reset transistor, and anamplification transistor.

In addition, each of the pixels 2 may have a shared pixel structure. Theshared pixel structure is composed of a plurality of photodiodes, aplurality of transfer transistors, a shared floating diffusion (floatingdiffusion region), and other shared individual pixel transistors. Thatis, in the shared pixel structure, the photodiodes and the transfertransistors constituting the plurality of unit pixels share otherindividual pixel transistors. A configuration example of the pixels 2will be described later with reference to FIG. 2.

The control circuit 8 receives an input clock and data for commanding anoperations mode or the like and outputs data such as the internalinformation of the solid-state imaging device 1. That is, based on avertical synchronization signal, a horizontal synchronization signal,and a master clock, the control circuit 8 generates a clock signal and acontrol signal that server as the bases of the operations of thevertical drive circuit 4, the column signal processing circuits 5, thehorizontal drive circuit 6, and the like. Then, the control circuit 8outputs the clock signal and the control signal thus generated to thevertical drive circuit 4, the column signal processing circuits 5, thehorizontal drive circuit 6, and the like.

The vertical drive circuit 4 is composed of, for example, a shiftregister, selects pixel drive wiring 10, and supplies a pulse fordriving the pixels 2 to the selected pixel drive wiring 10 to drive thepixels 2 on a line-by-line basis. That is, the vertical drive circuit 4sequentially selects and scans each of the pixels 2 of the pixel arrayunit 3 on a line-by-line basis and supplies a pixel signal based on asignal charge generated in the photoelectric conversion portion of eachof the pixels 2 according to a light receiving amount to the columnsignal processing circuit 5 via a vertical signal line 9.

The column signal processing circuits 5 are arranged for each column ofthe pixels 2 and performs signal processing such as noise reduction on asignal output from the pixels 2 of one line for each column of the pixel2. For example, the column signal processing circuits 5 perform signalprocessing such as CDS (Correlated Double Sampling) and AD conversionfor eliminating fixed pattern noise unique to the pixels 2.

The horizontal drive circuit 6 is composed of, for example, a shiftregister, sequentially outputs a horizontal scanning pulse to selecteach of the column signal processing circuits 5 by turns, and causeseach of the column signal processing circuits 5 to output an pixelsignal to a horizontal signal line 11.

The output circuit 7 performs signal processing on a signal sequentiallysupplied from each of the column signal processing circuits 5 via thehorizontal signal line 11 and outputs the processed signal. The outputcircuit 7 performs buffering only or various digital signal processingsuch as black level adjustment and column fluctuation correctionaccording to circumstances. An input/output terminal 13 sends andreceives signals to and from an outside.

The solid-state imaging device 1 configured as described above is a CMOSimage sensor called a column AD type in which the column signalprocessing circuits 5 for performing CDS processing and AD conversionprocessing are arranged on a pixel-column-by-pixel-column basis.

2. Circuit Configuration Example of Pixels

FIG. 2 shows a circuit configuration example of the pixels 2.

Each of the pixels 2 has a photodiode 41 serving as a photoelectricconversion element, a transfer transistor 42, a FD (Floating Diffusion)43, a reset transistor 44, an amplification transistor 45, and aselection transistor 46.

The photodiode 41 is a photoelectric conversion portion that generatesand accumulates a charge (signal charge) according to a received lightamount. The anode terminal of the photodiode 41 is grounded, and thecathode terminal thereof is connected to the FD 43 via the transfertransistor 42.

When the transfer transistor 42 is turned on by a transfer signal TRX,it reads a charge generated by the photodiode 41 and transfers the sameto the FD 43.

The FD 43 is a charge retention portion that retains a charge read fromthe photodiode 41 to be read as a signal. When the reset transistor 44is turned on by a reset signal RST, it discharges a charge accumulatedin the FD 43 to a drain (constant voltage source VDD) to reset thepotential of the FD 43.

The amplification transistor 45 outputs a pixel signal according to thepotential of the FD 43. That is, the amplification transistor 45constitutes a source follower circuit with a load MOS serving as aconstant current source 47 connected via a vertical signal line 9, and apixel signal indicating a level according to a charge accumulated in theFD 43 is output from the amplification transistor 45 to a column signalprocessing circuit 5 via the selection transistor 46. The constantcurrent source 47 is provided as, for example, part of the column signalprocessing circuit 5.

The selection transistor 46 is turned on when the pixel 2 is selected bya selection signal SEL, and outputs the pixel signal of the pixel 2 tothe column signal processing circuit 5 via the vertical signal line 9.Respective signal lines through which the transfer signal TRX, theselection signal SEL, and the reset signal RST are transmittedcorrespond to the pixel drive wiring 10 of FIG. 1.

The pixel 2 is configured as described above. The configuration of thepixel 2 is not limited to the above one, but other configurations of thepixel 2 may be employed.

For example, the circuit configuration of the pixel 2 shown in FIG. 2uses the four pixel transistors of the transfer transistor 42, the resettransistor 44, the amplification transistor 45, and the selectiontransistor 46. However, it may use the three pixel transistors excludingthe selection transistor 46. The respective pixel transistors shown inFIG. 2 operate as n-channel MOS transistors.

Hereinafter, a description will be given of a pixel structure thatprevents the degradation of color mixture in the solid-state imagingdevice 1 of the rear surface irradiation type in which on-chip lenseslarger in size than pixels are formed for every other pixel.

3. First Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 3 is a cross-sectional configuration view according to a firstembodiment of the pixels 2. FIG. 3 shows the cross-sectionalconfiguration of the plurality of pixels 2 arranged side by side in ahorizontal direction inside the pixel array unit 3.

The semiconductor substrate 12 is made of, for example, an n-typesilicon substrate serving as a first conductive type and has a thicknessof about 3 to 5 In FIG. 3, the upper side is the rear surface side ofthe semiconductor substrate 12 where light is incident and the lowerside is the front surface side thereof where pixel transistors areformed. Accordingly, the solid-state imaging device 1 employing thepixel structure of FIG. 3 is the CMOS image sensor of the rear surfaceirradiation type in which light is incident from the rear surface sideof the semiconductor substrate 12.

As shown in FIG. 3, in the semiconductor substrate 12, the photodiode 41formed by bonding together an n-type charge accumulation region 61serving as a first conductive type, a p-type dark current preventionregion 62 serving as a second conductive type, and a p+-type darkcurrent prevention region 63 is formed for each of the pixels 2. Here,“p+” of the dark current prevention region 63 indicates that impurityconcentration is higher than “p” of the dark current prevention region62.

A signal charge generated according to an incident light amount isaccumulated in the charge accumulation region 61. In addition, sinceelectrons generated at the interface of the semiconductor substrate 12rejoin with holes serving as a multiplicity of carriers inside the darkcurrent prevention regions 62 and 63, a dark current is prevented.

On the front surface side (lower side of FIG. 3) of the semiconductorsubstrate 12, a multilevel wiring layer 66 composed of a plurality ofpixel transistors Tr each performing the reading or the like of a chargeaccumulated in the photodiode 41, a plurality of wiring layers 64, andan interlayer insulation film 65 is formed. In addition, on the lowerside of the multilevel wiring layer 66, a support substrate 67 isattached.

Between the two adjacent photodiodes 41, a p+-type element separationlayer 68 is formed. The element separation layer 68 has the function ofelectrically separating the adjacent pixels from each other.

The element separation layer 68 has an embedded light-shielding portion71A embedded at a desired depth from the rear surface side of thesemiconductor substrate 12. The embedded light-shielding portion 71A isconnected to a light-shielding wall 71B formed in a color filter layer73 at the interface on the rear surface side of the semiconductorsubstrate 12, and the embedded light-shielding portion 71A and thelight-shielding wall 71B constitute a light-shielding portion 71. As thematerial of the light-shielding portion 71, a metal material such astungsten and aluminum may be, for example, used.

The entire surface on the rear surface side of the semiconductorsubstrate 12 is covered with a high dielectric constant film 72. Morespecifically, the side walls and the bottom sides of the embeddedlight-shielding portions 71A embedded in the element separation layers68 inside the semiconductor substrate 12 and the interfaces on the rearsurface side of the p-type dark current prevention regions 62 and theelement separation layers 68 are covered with the high dielectricconstant film 72. The high dielectric constant film 72 prevents physicaldamage caused when trenches serving as the embedded light-shieldingportions 71A are formed or pinning deviation caused on the peripheriesof the trenches when impurity is inactivated by ion irradiation. As thehigh dielectric constant film 72, hafnium oxide (HfO₂), tantalumpentoxide (Ta₂O₅), or zirconium dioxide (ZrO₂) may be, for example,used.

Color filters 73 colored in any of R (Red), G Green), B (Blue), and W(White) are formed over the photodiodes 41 on the rear surface side ofthe semiconductor substrate 12, and the light-shielding walls 71B areformed between (at the side portions of) the color filters 73 at therespective pixels 2. The color filters 73 colored in R, G, or B causeonly light having a prescribed wavelength corresponding to R, G, or Bamong incident light to be incident on the photodiodes 41. The colorfilters 73 colored in W cause incident light having all wavelengths tobe incident on the photodiodes 41. Note that when R, G, B, and W of thecolor filters 73 are not particularly distinguished from each other, thecolor filters 73 are also called color filter layers 73.

As shown in FIG. 3, on-chip lenses 74A larger in size than pixels 2 areformed on the upper surfaces of the color filter layers 73 for everyother pixel. Note that between the on-chip lenses 74A formed for everyother pixel, on-chip lens flattened layers 74B made of the same materialas the on-chip lenses 74A are formed.

In the following description, the on-chip lenses 74A and the on-chiplens flattened layers 74B are collectively called an on-chip lens layer74. The on-chip lens layer 74 may be made of, for example, a resinmaterial such as a styrene resin, an acrylic resin, a styrene-acryliccopolymer resin, and a siloxane resin.

In the example of FIG. 3, the color filter layers 73 at the pixels 2where the on-chip lenses 74A are present are the color filters 73colored in R, G, or B, and the color filter layers 73 at the pixels 2where the on-chip lenses 74A are absent are the color filters 73 coloredin W. However, as will be described later with reference to FIGS. 24 to27, the method of arranging the colors of the color filters 73 is notlimited to this example.

The upper surfaces of the color filters 73 colored in R, G, or B at thepixels 2 where the on-chip lenses 74A are present are the same in sizeas the on-chip lenses 74A. In a cross-sectional shape, as shown in FIG.3, each of the color filters 73 colored in R, G, or B at the pixels 2where the on-chip lenses 74A are present is formed in a trapezoidalshape whose upper side on the side of the on-chip lens 74A is the samein width as the on-chip lens 74A and whose lower side on the side of thephotodiode 41 is shorter than the upper side.

On the other hand, each of the color filters 73 colored in W at thepixels 2 where the on-chip lenses 74A are absent is formed in arectangular shape whose upper side on the side of the on-chip lensflattened layer 74B and the lower side on the side of the photodiode 41are the same in length.

Therefore, the cross section of each of the light-shielding walls 71Bformed between the adjacent color filters 73 is formed in a triangularshape whose side partially contacting the embedded light-shieldingportion 71A serves as its bottom side and whose height perpendicular tothe bottom side corresponds to the film thickness of the color filterlayers 73.

In other words, each of the light-shielding walls 71B is formed to havea slant surface such that the color filter 73 at the pixel 2 where theon-chip lens 74A is present has an opening made larger toward the upperlayer thereof close to the on-chip lens 74A and formed to have avertical surface at the pixel 2 where the on-chip lens 74A is absent.

FIG. 4A is a plan view as seen from the upper surfaces of the colorfilter layers 73. In addition, FIG. 4B is a cross-sectional view takenalong the line X-X′ of FIG. 3, and FIG. 4C is a cross-sectional viewtaken along the line Y-Y′ of FIG. 3.

In the pixel array unit 3, as shown in FIG. 4A, the color filters 73colored in R, G, or B where the on-chip lenses 74A are present and thecolor filters 73 colored in W where the on-chip lenses 74A are absentare arranged in a checkered pattern.

In addition, each of the color filters 73 colored in R, G, or B largerin size than the pixels 2 is formed in an octagonal shape or a shapeclose to a circle circumscribing the four corners of the pixel 2 formedin a square shape.

Each of the light-shielding walls 71B inside the color filter layers 73is formed as an equilateral octagonal or circular peripheral portion asshown in FIG. 4B, and each of the embedded light-shielding portions 71Ainside the semiconductor substrate 12 is formed on the boundary of therectangle pixel region of the pixel 2. When the pitch of the size of thepixels 2 is X, the opening diameter of the color filters colored in R,G, or B larger in size than the pixels 2 is √2X.

As described above, in the solid-state imaging device 1, the on-chiplenses 74A are formed on only the color filters 73 colored in R, G, or Band having a large opening and are not formed on the color filters 73colored in W and having a small opening. At the pixels 2 where theon-chip lenses 74A are present, light may be efficiently incident on thephotodiodes 41 with the incident light condensed. At the pixels 2 wherethe on-chip lenses 74A are absent, a difference in the sensitivitybetween the pixels 2 where the color filters 73 colored in R, G, or Bare arranged and the pixels 2 where the color filters 73 colored in Ware arranged may be further reduced since the on-chip lenses 74A are notprovided.

In addition, in the solid-state imaging device 1 according to the firstembodiment, it is possible to manufacture the pixels 2 having the twodifferent types of sensitivities for different purposed in such a waythat the pixels 2 having the two types of opening areas formed by thelight-shielding walls 71B are arranged in a checkered pattern.

Then, the pixels 2 having a small opening area are defined as W pixelswhere the color filters 73 colored in W are arranged, and the pixels 2having a large opening area are defined as the RGB pixels (R pixels, Gpixels, or B pixels) where the color filters 73 colored in R, G, or Bare arranged. Thus, it is possible to reduce a difference in thesensitivity between the W pixels and the RGB pixels and prevent areduction in dynamic range due to saturation. On this occasion, sincethe configuration inside the semiconductor substrate 12 including thephotodiodes 41 is common to all the pixels, other characteristicsincluding a saturation signal amount are the same in all the pixels.

Moreover, in the solid-state imaging device 1 according to the firstembodiment, it is possible to reflect and refract slant light incidenton the on-chip lenses 74A with the light-shielding walls 71B arrangedbetween the color filters 73 colored in R, G, B, or W to cause the lightto be incident on the photodiodes 41 in the same pixels without beingleaked.

Accordingly, even in the pixel structure of the rear surface irradiationtype in which the distance between the on-chip lenses 74A and thephotodiodes 41 is short, it is possible to prevent color mixture fromthe pixels 2 where the on-chip lenses 74A are arranged to the pixels 2where the on-chip lenses 74A are not arranged.

Furthermore, with the embedded light-shielding portions 71A embedded inthe element separation layers 68 inside the semiconductor substrate 12,it is possible to prevent the leakage of light into the adjacent pixelscaused when the incident light is diffracted.

Thus, in the solid-state imaging device 1 according to the firstembodiment described above, it is possible to prevent the degradation ofcolor mixture while achieving the pixel structure of the rear surfaceirradiation type in which the on-chip lenses 74A larger in size than thepixels are formed for every other pixel.

Note that in the pixel structure according to the first embodimentdescribed above, it is also possible to apply so-called pupil correctiontechnology in which the two-dimensional positions of the light-shieldingwalls 71B and the on-chip lenses 74A are deviated according to thedirection of the principal ray of light to correct shading at theperipheral pixels of the pixel array unit 3.

In addition, although the above example describes the case in which thenumber of the types of opening sizes is two, the number of the types ofthe opening sizes is not limited to two. For example, it may also bepossible to change the opening sizes in multiple stages such that thearea ratio (large opening size/small opening size) of the pixels 2having a large opening size to the pixels 2 having a small opening sizeapproximates one toward the periphery of the pixel array unit 3 tooptimize balance in the sensitivity between the pixels while givingconsideration to peripheral light reduction due to shading.

4. Method of Manufacturing Pixels According to First Embodiment

Next, a description will be given, with reference to FIGS. 5 to 18, ofthe method of manufacturing the pixels 2 according to the firstembodiment.

First, as shown in FIG. 5, the n-type charge accumulation region 61, thep-type dark current prevention region 62, and p+-type dark currentprevention region 63 constituting the photodiode 41 are formed for eachof the pixels 2, and the element separation layers 68 are formed insidethe semiconductor substrate 12. In addition, on the front surface sideof the semiconductor substrate 12, the multilevel wiring layer 66composed of the plurality of pixel transistors Tr, the plurality ofwiring layers 64, and the interlayer insulation film 65 is formed.

Next, as shown in FIG. 6, the support substrate 67 is bonded to theupper portion of the multilevel wiring layer 66 by an organic adhesiveor physical bonding using plasma irradiation.

Then, after the support substrate 67 and the semiconductor substrate 12bonded together are entirely turned upside down as shown in FIG. 7, thesemiconductor substrate 12 is polished by a physical polishing methoduntil the p-type dark current prevention regions 62 are exposed as shownin FIG. 8.

Next, as shown in FIG. 9, after a photoresist 91 is formed on the rearsurface side of the semiconductor substrate 12, the photoresist 91 ispatterned to form opening portions 92 in regions where the embeddedlight-shielding portions 71 of the element separation layers 68 are tobe formed.

Dry etching is performed using the patterned photoresist 91 as a mask,whereby the element separation layers 68 are digged by a desired depthto form the trench portions 93 as shown in FIG. 10. The depth of thetrench portions 93 may be formed such that slant light incident from therear surface side of the semiconductor substrate 12 is allowed to beshielded on the side of the light receiving surface.

After the trenches 93 are formed in the element separation layers 68 ofthe semiconductor substrate 12, the photoresist 91 is removed as shownin FIG. 11.

After that, as shown in FIG. 12, a light-shielding material 94 such astungsten is, for example, deposited by a CVD (Chemical Vapor Deposition)method or a PVD (Physical Vapor Deposition) method on the upper surfaceon the rear surface side of the semiconductor substrate 12 including thetrench portions 93.

Then, an etching operation is performed twice on the light-shieldingmaterial 94 deposited on the upper surface on the rear surface side ofthe semiconductor substrate 12, whereby the light-shielding walls 71Beach having a triangular cross section are formed.

Specifically, first, as shown in FIG. 13, a photoresist 95 is formed asthe first etching operation on the light-shielding material 94 andpatterned to form opening portions 96 in regions where the color filters73 colored in W are to be formed.

Then, as shown in FIG. 14, dry etching is performed using the patternedphotoresist 95 as a mask, whereby opening portions 97 are formedcorresponding to the regions where the color filters 73 colored in W areto be formed. In the first etching operation, dry etching is performedusing, for example, the mixed gas of SF₆/Cl₂ to form the vertical crosssections of the light-shielding walls 71B. After that, the photoresist95 is removed.

Next, in the second etching operation, as shown in FIG. 15, aphotoresist 98 having a film thickness larger than the light-shieldingmaterial 94 and having a prescribed width about the opening portion 97where the color filter 73 colored in W is to be formed is patterned.

Then, dry etching is performed using the patterned photoresist 98 as amask, whereby the light-shielding material 94 is etched to form theslant surfaces of the light-shielding walls 70B on the side of the RGBpixels as shown in FIG. 16. In the manner described above, the embeddedlight-shielding portions 71A embedded in the element separation layers68 and the light-shielding walls 71B formed in the color filter layers73 are formed. As the etching method of forming a taper angle, it ispossible to employ the method of using, for example, the mixed gas ofCF₄/Cl₂ as etching gas, change the mixing ratio to control a selectionratio with respect to the photoresist 98, and perform an etchingoperation on the photoresist 95 while moving the photoresist 95backward.

Next, the color filter layers 73 are formed as shown in FIG. 17, andthen the on-chip lens layer 74 is formed as shown in FIG. 18. Thus, thepixel structure shown in FIG. 3 is completed.

Note that in the example described above, the embedded light-shieldingportions 71A and the light-shielding walls 71B of the light-shieldingportions 71 are formed at the same time using the same light-shieldingmaterial 94. However, the embedded light-shielding portions 71A and thelight-shielding walls 71B may be made of different materials. On thisoccasion, the light-shielding walls 71B may be made of a metal materialdifferent from the material of the embedded light-shielding portions 71Aor be made of a low refractive index material having a lower refractiveindex than that of the color filter layers 73.

In the solid-state imaging device 1 according to the first embodimentdescribed above, the W pixels have the transmittance of incident lightabout three times as large as the RGB pixels. However, as shown in FIG.4A, since the opening area ratio of the RGB pixels having a largeopening to the W pixels having a small opening is about 0.21 time, the Wpixels are not first saturated.

Moreover, in the RGB pixels where the light-shielding walls 71B have theslant surface, a slant light component that is reflected by thelight-shielding walls 71B and does not reach the photodiodes 41 is morefrequently generated than the W pixels where the light-shielding walls71B have the vertical surface. Therefore, a difference in thesensitivity between the RGB pixels and the W pixels is further reduced,whereby the configuration having an excellent sensitivity balance isachieved.

In addition, with a change in the plane shape of the light-shieldingwalls 71B from the equilateral octagonal shape shown in FIG. 4B, it isalso possible to form any opening area and achieve the optimization of afurther sensitivity balance.

5. Second Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 19 is a cross-sectional configuration view according to a secondembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 3 accordingto the first embodiment described above are denoted by the same symbolsin FIGS. 19 to 23 and only components different from the components ofthe pixel structure shown in FIG. 3 will be described.

In comparison with the pixel structure according to the firstembodiment, a pixel structure according to the second embodiment shownin FIG. 19 does not have the on-chip lenses 74A provided on the colorfilter layers 73.

In recent years, since the manufacturing of on-chip lenses hasapproached its limit to suit to finer pixels, it is difficult tomanufacture the on-chip lenses with a desired curvature. Therefore, theconfiguration without the on-chip lenses 74A as shown in FIG. 19 maysolve the problem of such a manufacturing limit of the on-chip lenses.Since the light-shielding walls 71B are made of a material having alower refractive index than the surrounding color filter layers 73 or ametal material, light condensing efficiency may be sufficiently obtainedwithout the on-chip lenses 74A.

6. Third Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 20 is a cross-sectional configuration view according to a thirdembodiment of the pixels 2.

In the third embodiment shown in FIG. 20, light-shielding walls 71C areformed instead of the light-shielding walls 71B of FIG. 3. A pixelstructure according to the third embodiment is different from the pixelstructure according to the first embodiment in the height of thetriangular shapes of the cross sections of the light-shielding walls71C.

The height of the light-shielding walls 71C is formed to be lower thanthat of the light-shielding walls 71B according to the first embodiment,and the upper ends of the light-shielding walls 71C do not reach theupper ends of the color filter layers 73.

The color filter layers 73 desirably have a certain degree of thicknessto sufficiently disperse incident light. With such a configuration, thethickness of the color filter layers 73 may be set at a desired levelwithout suffering from a fluctuation in the height of thelight-shielding walls 71C. On this occasion, if the light-shieldingwalls 71C ensure a certain degree of height, the effect of preventingcolor mixture from the pixels 2 having a large opening to the pixels 2having a small opening and the effect of preventing the diffraction ofincident light at the pixels 2 having a small opening may besatisfactorily maintained when compared with the first embodiment.

7. Fourth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 21 is a cross-sectional configuration view according to a fourthembodiment of the pixels 2.

In the fourth embodiment shown in FIG. 21, light-shielding walls 71D areformed instead of the light-shielding walls 71B of FIG. 3. A pixelstructure according to the fourth embodiment is different from the pixelstructure according to the first embodiment in the cross-sectional shapeof the light-shielding walls 71D.

While the cross section of the light-shielding walls 71B according tothe first embodiment is formed in the triangular shape, the crosssection of the light-shielding walls 71D is formed in a trapezoidalshape as shown in FIG. 21.

If the cross section of the light-shielding walls 71D is formed in thetrapezoidal shape at the time of forming the light-shielding walls 71Dby dry etching, it is possible to form the light-shielding walls 71Dwithout causing a fluctuation in the height of the light-shielding walls71D. Accordingly, the pixel structure of the fourth embodiment mayachieve a robust configuration that is further free from a fluctuationin process.

8. Fifth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 22 is a cross-sectional configuration view according to a fifthembodiment of the pixels 2.

In the fifth embodiment shown in FIG. 22, light-shielding walls 71E areformed instead of the light-shielding walls 71B of FIG. 3. A pixelstructure according to the fifth embodiment is different from the pixelstructure according to the first embodiment in the cross-sectional shapeof the light-shielding walls 71E.

While the cross section of the light-shielding walls 71B according tothe first embodiment is formed in the triangular shape, the crosssection of the light-shielding walls 71E is formed in a square shapewhose side wall on the side of the RGB pixel having a large opening isalso vertical as shown in FIG. 22.

Although the effect of increasing sensitivity at the pixels 2 having alarge opening is not produced, it becomes easy to arbitrarily adjust theopening areas of the pixels 2 having a small opening with the protrusionamount of the light-shielding walls 71E. Thus, it becomes easy to adjusta difference in the sensitivity between the W pixels and the RGB pixelsand perform adjustment to prevent the W pixels from being saturatedearlier than the RGB pixels. In addition, since both side walls(vertical surfaces) of the light-shielding walls 71E may be etched in alump, it is possible to manufacture the pixels at a lower cost whencompared with the first embodiment.

9. Sixth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 23 is a cross-sectional configuration view according to a sixthembodiment of the pixels 2.

In the sixth embodiment shown in FIG. 23, light-shielding walls 71F areformed instead of the light-shielding walls 71B of FIG. 3. A pixelstructure according to the sixth embodiment is different from the pixelstructure according to the first embodiment in the cross-sectional shapeof the light-shielding walls 71F.

While the cross section of the light-shielding walls 71B according tothe first embodiment is formed in the vertical triangular shape whoseside wall on the side of the pixel having a small opening is vertical,the cross section of the light-shielding walls 71F is formed in atriangular shape whose side walls on both sides of the RGB pixel havinga large opening and the W pixel having a small opening are slantsurfaces as shown in FIG. 23.

With such a configuration, it is possible to adjust sensitivity at the Wpixels having a small opening and provide any difference in thesensitivity between the W pixels having a small opening and the RGBpixels having a large opening. In addition, when the slant surfaces ofboth the side walls are formed to be different in angle from each other,two etching operations are desirably performed. However, since both theside walls may be processed in a lump if they are formed to be the samein angle each other, the pixels may be manufactured at a lower cost.

10. Other Arrangement Examples of Color Filters

Next, a description will be given, with reference to FIGS. 24 to 27, ofother arrangement examples of the colors of the color filters 73.

In the example described above, the color filters 73 colored in R, G, orB are arranged at the pixels 2 having a large opening and the colorfilters 73 colored in W are arranged at the pixels 2 having a smallopening as shown in FIG. 4A.

The first method of arranging the color filters 73 shown in FIG. 4A isan arrangement method that gives priority to a dynamic range andsensitivity.

FIG. 24 is a plan view showing a second method of arranging the colorfilters 73.

According to the second method of arranging the color filters 73, thecolor filters 73 colored in G are arranged at all the pixels 2 having alarge opening and the color filters 73 colored in R or B are arranged atthe pixels 2 having a small opening.

In recent years, the manufacturing of finer pixels has been acceleratedwith an increase in the number of pixels and a reduction in the sizes ofsensors in the field of digital still cameras or the like, and thusconcerns are rising that brightness S/N ratio and color S/N ratioreduce. As a countermeasure for addressing the reduction in brightnessS/N ratio and color S/N ratio, it is effective to increase thesensitivity of G pixels identified by human eyes with high resolutionand apply a low-pass filter to R pixels and B pixels identified by humaneyes with low resolution to reduce noise. Accordingly, the second methodof arranging the color filters 73 shown in FIG. 24 is an arrangementmethod that contributes to the improvement in brightness S/N ratio andcolor S/N ratio.

FIG. 25 is a plan view showing a third method of arranging the colorfilters 73.

According to the third method of arranging the color filters 73, thecolor filters 73 colored in R or B are arranged at the pixels 2 having alarge opening and the color filters 73 colored in G are arranged at thepixels 2 having a small opening.

It is likely that scanners and copiers having a light source attachimportance to color reproducibility and color S/N ratio since brightnessS/N ratio is sufficiently ensured by the light source. In such anapplication, the third arrangement method shown in FIG. 25 is effective.

FIG. 26 is a plan view showing a fourth method of arranging the colorfilters 73.

According to the fourth method of arranging the color filters 73, thecolor filters 73 colored in R or B are arranged at the pixels 2 having alarge opening and the color filters 73 colored in W are arranged at thepixels 2 having a small opening.

As in the third arrangement method shown in FIG. 25, color S/N ratio maybe improved according to such an arrangement method. In addition, thearrangement method produces the effect of improving brightness S/N ratiowith the arrangement of W pixels instead of G pixels. Note that a Gsignal in the W pixels may be found by interpolation from pixelsadjacent to the W pixels.

FIG. 27 is a plan view showing a fifth method of arranging the colorfilters 73.

According to the fifth method of arranging the color filters 73, thecolor filters 73 colored in R, G, or B are arranged at all the pixels 2having a large opening and all the pixels 2 having a small opening.However, the color filters 73 colored in R, G, or B are arranged suchthat the color filters 73 at the pixels 2 having a large opening and theadjacent color filters 73 at the pixels 2 having a small opening are thesame in color.

According to such arrangement methods, high-sensitivity pixels and highdynamic-range pixels may be used for different purposes.

As described above, the first to fifth arrangement methods may bearbitrarily selected as the method of arranging the color filters 73 ofthe solid-state imaging device 1. In this regard, the same applies toother embodiments that will be described below.

According to the first to sixth embodiments of the pixels 2 describedabove, the leakage of light into the adjacent pixels due to thediffraction of the incident light may be prevented by the embeddedlight-shielding portions 71A embedded in the element separation layers68 inside the semiconductor substrate 12.

In addition, by the light-shielding walls 71B to 71F arranged betweenthe color filters 73 colored in R, G, B, or W, slant light incident onthe on-chip lenses 74A may be incident on the photodiodes 41 in the samepixels without being leaked.

Accordingly, the degradation of color mixture may be prevented in thepixel structure of the rear surface irradiation type in which theon-chip lenses 74A larger in size than the pixels 2 are formed for everyother pixel.

Next, the still other embodiments of the pixels 2 of the solid-stateimaging device 1 will be described.

Prior to the descriptions of the embodiments, a description will begiven, with reference to FIG. 28, of the problems to be solved by thetechnology of the present disclosure again.

FIG. 28 is a schematic cross-sectional configuration view showing apixel structure in a case in which the pixel structure of thefront-surface irradiation type in which on-chip lenses larger in sizethan pixels are formed for every other pixel is applied to arear-surface irradiation type.

In the case in which the pixel structure of the front-surfaceirradiation type in which the on-chip lenses larger in size than thepixels are formed for every other pixel is applied to the rear-surfaceirradiation type, incident light 102 passing through the peripheralportions of on-chip lenses 101 larger in size than pixels is notincident on expected central photodiodes 103 but is incident onunexpected left photodiodes 103, which causes color mixture.

In addition, a large vignetting component is generated when incidentlight 105 is reflected by inter-pixel light-shielding films 104 providedat the boundary portions between the pixels, which reduces sensitivity.

In view of these problems, the present disclosure may prevent thedegradation of color mixture and a reduction in sensitivity in the pixelstructure of the rear-surface irradiation type in which the on-chiplenses larger in size than the pixels are formed for every other pixel.

11. Seventh Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 29 is a cross-sectional configuration view according to a seventhembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 3 accordingto the first embodiment described above are denoted by the same symbolsin FIG. 29 and only components different from the components of thepixel structure shown in FIG. 3 will be described.

According to the seventh embodiment, the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12 as shown inFIG. 29. Each of the photodiodes 41 is shown in such a way that thecharge accumulation region 61 and the dark current prevention regions 62and 63 shown in FIG. 3 are simplified.

In addition, the seventh embodiment of FIG. 29 does not have theembedded light-shielding portions 71A of FIG. 3 and omits theillustration of the element separation layers 68. Moreover, the seventhembodiment also omits the illustrations of the multilevel wiring layer66 and the support substrate 67 formed on the front surface side of thesemiconductor substrate 12.

At pixel boundaries on the upper surface on the rear surface side of thesemiconductor substrate 12, inter-pixel light-shielding films 121 areformed to prevent the leakage of incident light into the adjacent pixels2. The inter-pixel light-shielding films 121 may be metal films made of,for example, tungsten, aluminum, copper, or the like.

On the upper surface on the rear surface side of the semiconductorsubstrate 12 including the inter-pixel light-shielding films 121, aflattened film 122 is formed. The flattened film 122 is formed by, forexample, coating an organic material such as a resin by rotation.Alternatively, the flattened film 122 may be formed by, for example,depositing an inorganic transparent film made of SiO₂ or the like andthen flattening the same with CMP (Chemical Mechanical Polishing).

Note that an anti-reflection film made of an oxide film or the like maybe formed between the flattened film 122 and the semiconductor substrate12.

As in the first embodiment of FIG. 3, the color filter layers 73 and thelight-shielding walls 71B are formed on the upper surface of theflattened film 122, and the on-chip lenses 74A and the on-chip lensflattened layers 74B are further formed on the color filter layers 73and the light-shielding walls 71B.

Note that in the example of FIG. 29, the color filters 73 colored in Ware arranged at all the pixels 2 having a small opening and the colorfilters 73 colored in R, G, and B are arranged sideways in a row at thepixels 2 having a large opening as the method of arranging the colors ofthe color filter layers 73. The arrangement method is not limited tothis, but any of the arrangement methods shown in FIG. 4A and FIGS. 24to 27 may be employed.

In a pixel structure according to the seventh embodiment configured asdescribed above, the light-shielding walls 71B are made of a lowrefractive index material or a metal material. Further, at the pixels 2where the on-chip lenses 74A are present, the side walls of thelight-shielding walls 71B are formed in slant surfaces such that thecolor filters 73 have an opening made larger toward the upper layersthereof close to the on-chip lenses 74A. On the other hand, at thepixels 2 where the on-chip lenses 74A are absent, the side walls of thelight-shielding walls 71B are formed in vertical surfaces.

Thus, as indicated by arrows in FIG. 30, incident light is entirelyreflected by the slant surfaces of the light-shielding walls 71B at thepixels 2 where the on-chip lenses 74A are present, which makes itpossible to prevent vignetting caused by the light-shielding walls 71Bthemselves and increase light condensing efficiency. In addition, sinceincident light is reflected by the light-shielding walls 71B, it ispossible to prevent vignetting caused by the inter-pixel light-shieldingfilms 121.

On the other hand, at the pixels 2 where the on-chip lenses 74A areabsent, the side walls of the light-shielding walls 71B are not taperedbut are formed in the vertical surfaces, whereby the openings at thelower surfaces of the color filters 73 are made the same in size as theopenings at the upper surfaces thereof.

Accordingly, even in the pixel structure of the rear-surface irradiationtype in which the distance between the on-chip lenses 74A and thephotodiodes 41 is short, it is possible to prevent color mixture fromthe pixels 2 where the on-chip lenses 74A are present to the pixels 2where the on-chip lenses 74A are absent.

That is, in the solid-state imaging device 1 according to the seventhembodiment, the degradation of color mixture may be prevented in thepixel structure of the rear-surface irradiation type in which theon-chip lenses larger in size than the pixels are formed for every otherpixel.

Note that as shown in FIG. 31, it is also possible to omit theinter-pixel light-shielding films 121 and the flattened film 122 formedbetween the semiconductor substrate 12 and the color filter layers 73.

12. First Method of Manufacturing Pixels According to Seventh Embodiment

Next, a description will be given, with reference to FIGS. 32A to 32Dand FIGS. 33A to 33D, of a first method of manufacturing the pixels 2according to the seventh embodiment.

First, as shown in FIG. 32A, the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12, and theinter-pixel light-shielding films 121 and the flattened film 122 areformed on the upper surface on the rear surface side of thesemiconductor substrate 12. Note that although omitted in the figures,the element separation layers 68 between the photodiodes 41 and themultilevel wiring layer 66 including the plurality of pixel transistorsTr on the front surface side of the semiconductor substrate 12 are alsoformed as in the embodiments described above.

Next, as shown in FIG. 32B, a light-shielding material 131 as thematerial of the light-shielding walls 71B is deposited on the uppersurface of the flattened film 122 with a prescribed film thickness. Thelight-shielding material 131 may be made of a low refractive indexmaterial or a metal material as in the embodiments described above.

Then, as shown in FIG. 32C, a photoresist 132 is formed on thelight-shielding material 131 and subsequently patterned to cause onlyregions where the color filters 73 colored in W are to be formed toremain.

Next, as shown in FIG. 32D, dry etching is performed under the etchingcondition that the patterned photoresists 132 have a tapered angle atthe peripheral portions thereof.

Then, as shown in FIG. 33A, a photoresist 133 is patterned with respectto the light-shielding materials 131 formed in a trapezoidal shape toopen the regions where the color filters 73 colored in W are to beformed.

Next, as shown in FIG. 33B, dry etching is performed under the etchingcondition that a tapered angle is not formed based on the patternedphotoresists 133. After the etching, the photoresists 133 are removed.

Then, as shown in FIG. 33C, the color filters 73 colored in G arepatterned at desired pixel regions, and the color filters colored in G,B, and W are also patterned at desired pixel regions in a prescribedorder.

Finally, the on-chip lenses 74A and the on-chip lens flattened layers74B are formed on the color filter layers 73, whereby the pixelstructure shown in FIG. 29 is completed.

13. Second Method of Manufacturing Pixels According to SeventhEmbodiment

Next, a description will be given, with reference to FIGS. 34A to 34Dand FIGS. 35A to 35D, of a second method of manufacturing the pixels 2according to the seventh embodiment.

First, as shown in FIG. 34A, the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12, and theinter-pixel light-shielding films 121 and the flattened film 122 areformed on the upper surface on the rear surface side of thesemiconductor substrate 12. The above step is the same as that of FIG.32A.

Next, as shown in FIG. 34B, polysilicon 141 is, for example, depositedon the upper surface of the flattened film 122 with the same filmthickness as that of the color filter layers 73 that will be formedlater. Note that since the material deposited here is to be finallyremoved, any material other than polysilicon may be used so long as aselective ratio to the material is ensurable.

Then, as shown in FIG. 34C, the polysilicon 141 is patterned to causeonly regions where the color filters 73 colored in W are to be formed toremain. The remaining portions of the polysilicon 141 serve as bases forforming the light-shielding walls 71B.

Next, as shown in FIG. 34D, a light-shielding material 142 as thematerial of the light-shielding walls 71B is deposited on the uppersurfaces of the flattened film 122 and the polysilicon 141 with aprescribed film thickness. The light-shielding material 142 may be madeof a low refractive index material or a metal material as in theembodiments described above.

Then, as shown in FIG. 35A, the desired regions of the light-shieldingmaterial 142 are removed by dry etching. On this occasion, since thelight-shielding material 142 is deposited with a large thickness at theperipheral portions of the polysilicon 141 serving as the bases, thelight-shielding walls 71B like side walls may be formed only byentire-surface etching.

After the light-shielding walls 71B are formed, the polisilicon 141serving as the bases is removed as shown in FIG. 35B.

The following steps of FIGS. 35C and 35D are the same as those of FIGS.33C and 33D described above. That is, the color filters 73 of therespective colors are formed between the light-shielding walls 71B andthen the on-chip lenses 74A and the on-chip lens flattened layers 74Bare formed, whereby the pixel structure shown in FIG. 29 is completed.

The pixel structure according to the seventh embodiment shown in FIG. 29may be formed by the first or second manufacturing method described withreference to FIGS. 32A to 32D to FIGS. 35A to 35D. Thus, the pixelstructure that prevents the degradation of color mixture may beachieved.

14. Eighth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 36 is a cross-sectional configuration view according to an eighthembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 3 accordingto the first embodiment described above are denoted by the same symbolsin FIG. 36 and only components different from the components of thepixel structure shown in FIG. 3 will be described.

According to the eighth embodiment, the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12 as shown inFIG. 36. Each of the photodiodes 41 is shown in such a way that thecharge accumulation region 61 and the dark current prevention regions 62and 63 shown in FIG. 3 are simplified.

In addition, the eighth embodiment of FIG. 36 does not have the embeddedlight-shielding portions 71A of FIG. 3 and omits the illustration of theelement separation layers 68. Moreover, the eighth embodiment also omitsthe illustrations of the multilevel wiring layer 66 and the supportsubstrate 67 formed on the front surface side of the semiconductorsubstrate 12.

On the upper surface on the rear surface side of the semiconductorsubstrate 12, a passivation film 151 is deposited. As the material ofthe passivation film 151, a silicon nitride film (SiN) or the like maybe, for example, used.

On the upper surface of the passivation film 151, flattened films 152are formed on a pixel-by-pixel basis. More specifically, the flattenedfilms 152 are formed to be the same in size as the pixels 2 at thepixels 2 where the on-chip lenses 74A are present, and the flattenedfilms 152 are formed to be the same in width as the on-chip lensflattened layers 74 at the pixels 2 where the on-chip lenses are absent.As the material of the flattened films 152, an organic material such asa resin having high transparency may be, for example, used.

The color filters 153 colored in R, G, or B are formed on the uppersurfaces of the flattened films 152, and the on-chip lenses 74A and theon-chip lens flattened layers 74B are formed on the color filters 153.

Each of the color filters 153 at the pixels 2 where the on-chip lenses74A are present is formed to have a trapezoidal cross section whoseupper side of the color filter 153 is the same in width as the on-chiplens 74A and whose lower side is the same in width as the pixel 2. Notethat the width of the lower side of each of the color filters 153 at thepixels 2 where the on-chip lenses 74A exist is not necessarily the samein size as the pixel 2 but may only be shorter than the upper side ofeach of the color filters 153. In other words, the side walls of each ofthe color filters 153 at the pixels 2 where the on-chip lenses 74A arepresent may be slant surfaces that do not hinder incident light passingthrough the end of the on-chip lens 74A.

On the other hand, each of the color filters 153 at the pixels 2 wherethe on-chip lenses 74A are absent is formed to have a substantiallytrapezoidal cross section whose upper side is the same in width as theon-chip lens flattened layer 74B and also formed at the peripheralportion of the pixel 2 on the passivation film 151 where the flattenedfilm 152 is absent. Accordingly, at each of the pixels 2 where theon-chip lenses 74A are absent, the film thickness of the color filter153 at the peripheral portion of the pixel 2 is the same as or largerthan that of the color filter 153 at the central portion thereof. Inaddition, at each of the pixels 2 where the on-chip lenses 74A areabsent, the film thickness of the color filter 153 at the centralportion of the pixel 2 is the same as that of the color filter 153 ateach of the pixels 2 where the on-chip lenses 74A are present and commonto all the pixels.

In the cross-sectional structure of the pixels 2 according to the eighthembodiment configured as described above, each of the color filters 153at the pixels 2 where the on-chip lenses 74A are absent is formed tohave a larger thickness at the peripheral portion of the pixel 2 than atthe central portion thereof.

Thus, since incident light as indicated by arrows in FIG. 37, whichpasses through the vicinities of the portions of the on-chip lenses 74Aprotruding to the adjacent pixels 2, passes through the film thicknessportions of the color filters 153, the color mixture component of theincident light may be sufficiently attenuated.

The flattened films 152 the same in size as the on-chip lens flattenedlayers 74B are formed at the central portions at the pixels 2 where theon-chip lenses 74A are absent, whereby the film thickness of the colorfilters 153 are made common to all the pixels 2. Thus, since the filmthickness of the color filters 153 is not large at regions whereincident light is received, light condensing efficiency may beincreased.

In addition, since each of the color filters 153 at the pixels 2 wherethe on-chip lenses 74 are present is formed to have a reversetrapezoidal shape whose upper surface is the same in size as the on-chiplens 74 and whose lower surface is the same in size as the pixel 2, thedegradation of color mixture may be prevented without reducing lightcondensing efficiency.

15. Method of Manufacturing Pixels According to Eighth Embodiment

Next, a description will be given, with reference to FIGS. 38A to 38Dand FIGS. 39A to 39D, of the method of manufacturing the pixels 2according to the eighth embodiment.

First, as shown in FIG. 38A, the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12, and thepassivation film 151 and a transparent material 161 for forming theflattened films 152 are deposited on the upper surface on the rearsurface side of the semiconductor substrate 12. Note that althoughomitted in the figures, the element separation layers 68 between thephotodiodes 41 and the multilevel wiring layer 66 including theplurality of pixel transistors Tr on the front surface side of thesemiconductor substrate 12 are also formed as in the embodimentsdescribed above.

Then, as shown in FIG. 38B, after a photoresist 162 is deposited on theentire surface on the upper side of the transparent material 161 andpatterned corresponding to the regions of the flattened films 152, thetransparent material 161 is etched. By the etching, the flattened films152 are formed.

As described above, the flattened films 152 are formed to be the same insize as the pixels 2 at the pixels 2 where the on-chip lenses 74A arepresent and formed to be smaller in size than the pixels 2, i.e., thesame in size as the on-chip lens flattened layers 74B, which will beformed later, at the pixels 2 where the on-chip lenses 74A are absent.

At each of the pixels 2 where the on-chip lenses 74A are absent, thecolor filter 153 is formed at the peripheral portion of the pixel 2where the flattened film 152 is not formed. Accordingly, the filmthickness of the color filters 153 having the effect of attenuating thecolor mixture component of incident light depends on the patterning andetching amount of the photoresist 162.

Next, as shown in FIG. 38C, after the photoresists 162 are removed, acolor filter material 163 colored in a prescribed color (R in FIG. 38C)is coated on the upper surfaces of the passivation film 151 and theflattened films 152.

Then, as shown in FIG. 38D, only the desired regions of the R colorfilter material 163 coated on the entire surface are exposed. Afterthat, as shown in FIG. 39A, the unnecessary portions of the R colorfilter material 163 are removed.

Next, a photoresist 164 having a prescribed size is patterned and etchedat the central portions of the pixels 2 on the upper surfaces of the Rcolor filter materials 163, whereby the R color filter materials 163 aretapered at the peripheral portions of the pixels 2. Thus, the colorfilters 153 colored in R are completed.

After the color filters 153 at the pixels 2 where the on-chip lenses 74Aare not to be formed are first formed as described above, the colorfilters 153 colored in G at the pixels 2 where the on-chip lenses 74Aare to be formed are formed as shown in FIG. 39C.

Finally, as shown in FIG. 39D, the on-chip lenses 74A and the on-chiplens flattened layers 74B are formed on the color filters colored in R,G, and B, whereby the pixel structure shown in FIG. 36 is completed.

16. Ninth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 40 is a cross-sectional configuration view according to a ninthembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 36according to the eighth embodiment described above are denoted by thesame symbols in FIG. 40 and only components different from thecomponents of the pixel structure shown in FIG. 36 will be described.

A pixel structure according to the ninth embodiment is different fromthe pixel structure according to the eighth embodiment shown in FIG. 36in that transparent films 171 made of a material having hightransparency are formed instead of the flattened films 152 on the uppersurface of the passivation film 151 at the pixels 2 where the on-chiplenses 74A are absent.

In the pixel structure shown in FIG. 40, etching is performed based onthe patterned photoresists 162 of FIG. 38B to cause only the flattenedfilms 152 to remain at the pixels 2 where the on-chip lenses 74A arepresent. Then, on the passivation film 151 at the pixels 2 where theon-chip lenses 74A are absent, the transparent films 171 made of amaterial having high transparency may be patterned and formed. Othersteps are the same as the steps of the manufacturing method according tothe eighth embodiment described with reference to FIGS. 38A to 38D andFIG. 39A to 39D.

In the pixel structure according to the ninth embodiment, thetransparent films 171 made of a material having high transparency areemployed instead of the flattened films 152 at the pixels 2 where theon-chip lenses 74A are absent. Therefore, compared with the pixelstructure according to the eighth embodiment, incident light may be moreefficiently condensed.

17. Tenth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 41 is a cross-sectional configuration view according to a tenthembodiment of the pixels 2 of the solid-state imaging device 1.

Note that components corresponding to the components of FIG. 40according to the ninth embodiment described above are denoted by thesame symbols in FIG. 41 and only components different from thecomponents of the pixel structure shown in FIG. 40 will be described.

A pixel structure according to the tenth embodiment is different fromthe pixel structure according to the ninth embodiment shown in FIG. 40in that transparent films 181 having a trapezoidal cross-sectional shapeare formed instead of the transparent films 171 having a rectangularcross-sectional shape on the upper surface of the passivation film 151at the pixels 2 where the on-chip lenses 74A are absent.

With the trapezoidal cross-sectional shape of the transparent films 181,the shape of the color filters 153 formed on the transparent films 181may be controlled. The trapezoidal transparent films 181 may be formedunder the control of etching conditions. Other manufacturing steps arethe same as the manufacturing steps of the pixel structure according tothe ninth embodiment described above.

In the pixel structure according to the tenth embodiment, thetransparent films 181 made of a material having high transparency areemployed instead of the flattened films 152 at the pixels 2 where theon-chip lenses 74A are absent. Therefore, compared with the pixelstructure according to the eighth embodiment, incident light may be moreefficiently condensed.

Note that as the material of the transparent films 171 or 181, amaterial having high transparency such as an oxide film (SiO₂) may be,for example, used. However, if a material having a high refractive indexsuch as a nitride film (SiN) and an oxynitride film (SiON) is, forexample, used, condensing efficiency may be further increased.

18. Eleventh Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 42 is a cross-sectional configuration view according to an eleventhembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 40according to the ninth embodiment described above are denoted by thesame symbols in FIG. 42 and only components different from thecomponents of the pixel structure shown in FIG. 40 will be described.

A pixel structure according to the eleventh embodiment is different fromthe pixel structure according to the ninth embodiment shown in FIG. 40in that the passivation film 151 is not formed on the entire surface onthe rear surface side of the semiconductor substrate 12. Like this, itis also possible to omit the passivation film 151.

Note that the pixel structure having the trapezoidal transparent films181 shown in FIG. 41 may also omit the passivation film 151.

19. Twelfth Embodiment of Pixels

(Cross-Sectional View of Pixels)

FIG. 43 is a cross-sectional configuration view according to a twelfthembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 42according to the eleventh embodiment described above are denoted by thesame symbols in FIG. 43 and only components different from thecomponents of the pixel structure shown in FIG. 42 will be described.

A pixel structure according to the twelfth embodiment is different fromthe pixel structure according to the eleventh embodiment shown in FIG.42 in that inter-pixel light-shielding films 191 are formed at pixelboundary portions at the interface on the rear surface side of thesemiconductor substrate 12. By the inter-pixel light-shielding films191, the leakage of light from the adjacent pixels 2 may be reliablyprevented.

In the solid-state imaging device 1 according to the eighth to twelfthembodiments described above, the degradation of color mixture may beprevented in the pixel structure of the rear surface irradiation type inwhich the on-chip lenses larger in size than the pixels are formed forevery other pixel.

20. Thirteenth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 44 is a cross-sectional configuration view according to athirteenth embodiment of the pixels 2.

Note that components corresponding to the components of FIG. 3 accordingto the first embodiment described above are denoted by the same symbolsin FIG. 44 and only components different from the components of thepixel structure shown in FIG. 3 will be described.

According to the thirteenth embodiment, the photodiodes 41 are formed ona pixel-by-pixel basis inside the semiconductor substrate 12 as in theembodiments described above. Each of the photodiodes 41 is shown in sucha way that the charge accumulation region 61 and the dark currentprevention regions 62 and 63 shown in FIG. 3 are simplified.

In addition, the thirteenth embodiment of FIG. 44 does not have theembedded light-shielding portions 71A of FIG. 3 and omits theillustration of the element separation layers 68. Moreover, thethirteenth embodiment also omits the illustrations of the multilevelwiring layer 66 and the support substrate 67 formed on the front surfaceside of the semiconductor substrate 12.

A protection film 201 is formed with a prescribed thickness on the uppersurface on the rear surface side of the semiconductor substrate 12, andcolor filters 202 are formed on the protection film 201. Moreover, overthe color filters 202, on-chip lenses 203A are formed on the uppersurface of a heightened on-chip lens layer for every other pixel.

The protection film 201 is formed to have a different thickness betweenthe pixels 2 where the on-chip lenses 203A are present and the pixels 2where the on-chip lenses 203A are absent. Specifically, the thickness ofthe protection film. 201 at the pixels 2 where the on-chip lenses 203Aare present is equivalent to the sum of the thickness of the protectionfilm 201 and the thickness of the color filters 202 at the pixels 2where the on-chip lenses 203A are absent. Further, the color filters 202formed on the protection film 201 at the pixels 2 where the on-chiplenses 203A are present are formed to be larger in size than the pixels2 so as to be superimposed on the color filters 202 at the pixels 2where the on-chip lenses 203A are absent.

In the example of FIG. 44, the color filters 202 colored in R are formedat the pixels 2 where the on-chip lenses 203A are absent, and the colorfilters 202 colored in G are formed at the pixels 2 where the on-chiplenses 203A are present. The arrangement of the colors of the colorfilters 202 is not limited to this example, but the various arrangementmethods shown in FIG. 4A and FIGS. 24 to 27 may be employed.

The protection film 201 may be, for example, an inorganic transparentfilm made of SiO₂ or the like. The on-chip lenses 203A and the on-chiplens layer 203 are made of, for example, a silicon nitride film (SiN) ora resin material such as a styrene resin, an acrylic resin, astyrene-acryl copolymer resin, and a siloxane resin.

In a pixel structure according to the thirteenth embodiment, the on-chiplens layer 203 is formed to heighten the pixel structure as shown inFIG. 45 to optimize a focal distance, whereby incident light passingthrough the on-chip lenses 203 formed to be larger in size than thepixels 2 may be prevented from being incident on the photodiodes 41 atthe adjacent pixels 2.

In addition, in the pixel structure according to the thirteenthembodiment, the color filters 202 at the pixels 2 where the on-chiplenses 203A are present are formed to be superimposed on the colorfilters 202 at the adjacent pixels 2 where the on-chip lenses 203A areabsent. As shown in FIG. 45, the superimposed portions may attenuateincident light leaking into the adjacent pixels 2.

Accordingly, in the pixel structure according to the thirteenthembodiment, the degradation of color mixture may be prevented in thepixel structure of the rear surface irradiation type in which theon-chip lenses larger in size than the pixels are formed for every otherpixel.

(Superimposed Amount S of Color Filters)

A description will be given, with reference to FIG. 46, of the optimumvalue of the superimposed amount S between the color filter 202 at thepixel 2 where the on-chip lens 203A is present and the color filters 202at the adjacent pixels 2 where the on-chip lenses 203A are absent.

The superimposed amount S may be calculated by defining the width of thecolor filter 202 right below the on-chip lens 203A such that all lightcondensed into the pixel 2 right below the on-chip lens 203A passesthrough the color filter 202 right below the on-chip lens 203A.

More specifically, when consideration is given to ideal condensing withthe on-chip lens 203A as shown in FIG. 46, the minimum value of thesuperimposed amount S of the color filter 202 may be calculated by thefollowing expression.

S=h·(D−W)/2H

∵S=h·tan θ, tan θ=(D−W)/2H

Here, H represents a height from the interface on the rear surface sideof the semiconductor substrate 12 to the uppermost surface of theon-chip lens layer 203, and h represents a height from the interface onthe rear surface side of the semiconductor substrate 12 to the uppermostsurface of the color filter 202 right below the on-chip lens 203A. Inaddition, W represents the width of the pixel 2, and D represents thewidth of the on-chip lens 203A.

21. Method of Manufacturing Pixels According to Thirteenth Embodiment

Next, a description will be given, with reference to FIGS. 47A to 47Dand FIGS. 48A to 48D, of the method of manufacturing the pixels 2according to the thirteenth embodiment.

First, as shown in FIG. 47A, the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12, and theprotection film 201 is formed with a prescribed thickness on the entiresurface on the rear surface side of the semiconductor substrate 12. Notethat although omitted in the figures, the element separation layers 68between the photodiodes 41 and the multilevel wiring layer 66 includingthe plurality of pixel transistors Tr are also formed as in theembodiments described above.

Then, as shown in FIG. 47B, a photoresist 211 is deposited on the entiresurface on the upper side of the protection film 201 and patterned toremain only at the pixels 2 where the on-chip lenses 74A are to beformed, and the protection film 201 is etched. By the etching, theprotection film 201 is formed to have a larger thickness at the pixels 2where the on-chip lenses 74A are to be formed than at the pixels 2 wherethe on-chip lenses 74A are not to be formed.

Next, as shown in FIG. 47C, after the removal of the photoresist 211, anR color filter material 212 formed at the pixels 2 where the on-chiplenses 74A are not to be formed is coated by rotation.

Then, as shown in FIG. 47D, only the desired regions of the R colorfilter material 212 coated by rotation are exposed. After that, as shownin FIG. 48A, the unnecessary portions of the R color filter material 212are removed. Thus, the color filters 202 colored in R are completed atthe pixels 2 where the on-chip lenses 74A are not to be formed.

Next, as shown in FIG. 48B, a G color filter material 213 formed at thepixels 2 where the on-chip lenses 74A are not to be formed is coated byrotation.

Then, as shown in FIG. 48C, only the desired regions of the G colorfilter material 213 coated by rotation are exposed. After that, as shownin FIG. 48D, the unnecessary portions of the G color filter material 213are removed. Thus, the color filters 202 colored in G are completed atthe pixels 2 where the on-chip lenses 74A are to be formed.

After that, the on-chip lens layer 203 and the on-chip lenses 203A areformed on the color filters 202 at the respective colors 2, whereby thepixel structure shown in FIG. 44 is completed.

22. Fourteenth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 49 is a cross-sectional configuration view according to afourteenth embodiment of the pixels 2.

Note that components corresponding to the components of FIG. 44according to the thirteenth embodiment described above are denoted bythe same symbols in FIG. 49 and only components different from thecomponents of the pixel structure shown in FIG. 44 will be described.

In a pixel structure according to the fourteenth embodiment, aprotection film 221 formed on the upper surface on the rear surface sideof the semiconductor substrate 12 has the same thickness between thepixels 2 where the on-chip lenses 203A are present and the pixels 2where the on-chip lenses 203A are absent.

Further, in the pixel structure according to the fourteenth embodiment,photosensitive transparent resin films 222 are formed between theprotection film 221 and the color filters 202 colored in G at the pixels2 where the on-chip lenses 203A are present. Like this, the stepsbetween the pixels 2 where the on-chip lenses 203A are present and thepixels 2 where the on-chip lenses 203A are absent may be formed by anymaterial other than the protection film 221.

23. Method of Manufacturing Pixels According to Fourteenth Embodiment

A description will be given, with reference to FIGS. 50A to 50E andFIGS. 51A to 51D, of the method of manufacturing the pixels 2 accordingto the fourteenth embodiment.

As shown in FIG. 50A, after the photodiodes 41 are formed on apixel-by-pixel basis inside the semiconductor substrate 12 and theprotection film 221 is formed on the entire surface on the rear surfaceside of the semiconductor substrate 12, a photosensitive transparentresin layer 231 is laminated with a prescribed film thickness. Note thatalthough omitted in the figures, the element separation layers 68between the photodiodes 41 and the multilevel wiring layer 66 includingthe plurality of pixel transistors Tr are also formed as in theembodiments described above.

Then, as shown in FIG. 50B, the photosensitive transparent resin layer231 is exposed only at the pixels 2 where the on-chip lenses 203A are tobe formed. As a result, as shown in FIG. 50C, the photosensitivetransparent resin films 222 are formed only at the pixels 2 where theon-chip lenses 203A are to be formed.

The following steps are the same as the manufacturing steps of the pixelstructure according to the thirteenth embodiment described above.

That is, as shown in FIG. 50D, an R color filter material 212 formed atthe pixels 2 where the on-chip lenses 74A are not to be formed is coatedby rotation.

Then, as shown in FIG. 50E, only the desired regions of the R colorfilter material 212 coated by rotation are exposed. After that, as shownin FIG. 51A, the unnecessary portions of the R color filter material 212are removed. Thus, the color filters 202 colored in R are completed atthe pixels 2 where the on-chip lenses 74A are not to be formed.

Next, as shown in FIG. 51B, a G color filter material 213 formed at thepixels 2 where the on-chip lenses 74A are not to be formed is coated byrotation.

Then, as shown in FIG. 51C, only the desired regions of the G colorfilter material 213 coated by rotation are exposed. After that, as shownin FIG. 51D, the unnecessary portions of the G color filter material 213are removed. Thus, the color filters 202 colored in G are completed atthe pixels 2 where the on-chip lenses 74A are to be formed.

After that, the on-chip lens layer 203 and the on-chip lenses 203A areformed on the color filters 202 at the respective colors 2, whereby thepixel structure shown in FIG. 49 is completed.

24. Fifteenth Embodiment of Pixels

(Cross-Sectional Configuration View of Pixels)

FIG. 52 is a cross-sectional configuration view according to a fifteenthembodiment of the pixels 2.

Note that components corresponding to the components of FIG. 49according to the fourteenth embodiment described above are denoted bythe same symbols in FIG. 52 and only components different from thecomponents of the pixel structure shown in FIG. 49 will be described.

In a pixel structure according to the fifteenth embodiment, colorfilters 241 colored in G including the portions of the photosensitivetransparent resin films 222 according to the fourteenth embodiment shownin FIG. 49 are formed. Color filters 241 colored in R at the pixels 2where the on-chip lenses 203A are absent are the same as the colorfilters 202 colored in R according to the fourteenth embodiment shown inFIG. 49. Such a pixel structure causes a difference in spectralcharacteristics due to a difference in the film thickness of the colorfilters 241 between the pixels 2 where the on-chip lenses 203A arepresent and the pixels 2 where the on-chip lenses 203A are absent buthas the advantage of less manufacturing steps.

In the fourteenth and fifteenth embodiments described above, the on-chiplens layer 203 is formed to heighten the pixel structure to optimize afocal distance, and the color filters 202 (241) at the pixels 2 wherethe on-chip lenses 203A are present are formed to be superimposed on thecolor filters 202 (241) at the adjacent pixels 2 where the on-chiplenses 203A are absent. Accordingly, the degradation of color mixturemay be prevented in the pixel structure of the rear surface irradiationtype in which the on-chip lenses larger in size than the pixels areformed for every other pixel.

The arrangement of the colors of the color filters 202 (241) is notlimited to this example in the fourteenth and fifteenth embodimentsdescribed above, but the various arrangement methods shown in FIG. 4Aand FIGS. 24 to 27 may be employed.

25. Application Example to Electronic Apparatuses

The application of the technology of the present disclosure is notlimited to solid-state imaging devices. In other words, the technologyof the present disclosure is applicable to overall electronicapparatuses having solid-state imaging devices as image capturingportions (photoelectric conversion portions) such as imaging apparatusesincluding digital still cameras and video cameras, mobile terminalapparatuses having imaging functions, and copiers having solid-stateimaging devices as image capturing portions. The solid-state imagingdevices may be of a one-chip form or a module-like form having animaging function and having an imaging unit and a signal processing unitor an optical system packaged therein.

FIG. 53 is a block diagram showing a configuration example of an imagingapparatus serving as an electronic apparatus according to an embodimentof the present disclosure.

An imaging apparatus 300 of FIG. 53 has an optical unit 301 including agroup of lenses, a solid-state imaging device (imaging device) employingthe configuration of the solid-state imaging device 1 of FIG. 1, and aDSP (Digital Signal Processor) circuit 303 serving as a camera signalprocessing circuit. In addition, the imaging apparatus 300 has a framememory 304, a display unit 305, a recording unit 306, an operation unit307, and a power supply unit 308. The DSP circuit 303, the frame memory304, the display unit 305, the recording unit 306, the operation unit307, and the power supply unit 308 are connected to each other via a busline 309.

The optical unit 301 captures incident light (image light) from asubject and forms the same on the imaging surface of the solid-stateimaging device 302. The solid-state imaging device 302 converts thelight amount of incident light formed on the imaging surface by theoptical unit 301 into an electric signal on a pixel-by-pixel basis andoutputs the converted electric signal as a pixel signal. As thesolid-state imaging device 302, the solid-state imaging device 1 of FIG.1, i.e., the solid-state imaging device of the rear-surface irradiationtype in which the on-chip lenses larger in size than the pixels areformed for every other pixel to prevent the degradation of color mixturemay be used.

The display unit 305 is made of, for example, a panel display devicesuch as a liquid crystal panel and an organic EL (Electro Luminescence)panel and displays moving images or still images captured by thesolid-state imaging device 302. The recording unit 306 records movingimages or still images captured by the solid-state imaging device 302 ona recording medium such as a hard disk and a semiconductor memory.

The operation unit 307 issues an operating command for the variousfunctions of the imaging apparatus 300 according to user's operations.The power supply unit 308 appropriately supplies various power suppliesserving as power supplies for operating the DSP circuit 303, the framememory 304, the display unit 305, the recording unit 306, and theoperation unit 307 to these supply targets.

As described above, the degradation of color mixture may be preventedwhen the solid-state imaging device 1 described above is used as thesolid-state imaging device 302. Accordingly, the high quality ofcaptured images may be achieved even in the imaging apparatuses 300 ofcamera modules or the like for mobile equipment such as video cameras,digital still cameras, and mobile phones.

The example described above refers to the solid-state imaging device inwhich the first conductive types serve as n-types, the second conductivetypes serve as p-types, and the electrons serve as signal charges.However, the technology of the present disclosure may also be applied tosolid-state imaging devices in which holes serve as signal charges. Thatis, with the first conductive types serving as p-types and the secondconductive types as n-types, the respective semiconductor regionsdescribed above may be constituted of semiconductor regions having thereverse conductive types.

In addition, the application of the technology of the present disclosureis not limited to solid-state imaging devices that detect thedistribution of the incident light amounts of visible light and capturethe same as images, but the technology of the present disclosure isapplicable to solid-state imaging devices that capture the distributionof the incident amounts of infrared rays, X-rays, or particles as imagesand is applicable, in a broad sense, to overall solid-state imagingdevices (physical amounts distribution detection devices) such as fingerprint detection sensors that detect the distribution of other physicalamounts such as pressure and capacitances and capture the same asimages.

The embodiments of the present disclosure are not limited to theembodiments described above but may be modified in various ways insofaras they are within the scope of the present disclosure.

For example, all or some of the plurality of embodiments described abovemay be combined together.

Note that the effects described in the specification are only forillustration purposes and the effects of the present disclosure are notlimited to them. That is, effects other than those described in thespecification may be produced.

Note that the present technology may also employ the followingconfigurations.

(1) A solid-state imaging device, including:

a plurality of pixels arranged in a matrix pattern, each of the pixelshaving a photoelectric conversion portion configured tophotoelectrically convert light incident from a rear surface side of asemiconductor substrate; and

a plurality of on-chip lenses arranged for every other pixel, theon-chip lenses being larger in size than the pixels, in which

each of color filters at the pixels where the on-chip lenses are presenthas a cross-sectional shape whose upper side close to the on-chip lensis the same in width as the on-chip lens and whose lower side close tothe photoelectric conversion portion is shorter than the upper side.

(2) The solid-state imaging device according to (1), in which

a film thickness at a peripheral portion of each of the color filters atthe pixels where the on-chip lenses are absent is larger than a filmthickness at a central portion thereof.

(3) The solid-state imaging device according to (1) or (2), in which

each of the color filters at the pixels where the on-chip lenses areabsent is formed on a transparent film made of a material having hightransparency.

(4) The solid-state imaging device according to (3), in which

the transparent film has a trapezoidal cross section.

(5) The solid-state imaging device according to any one of (1) to (4),in which

each of the color filters at the pixels where the on-chip lenses arepresent has a trapezoidal cross section.

(6) The solid-state imaging device according to any one of (1) to (5),further including

a plurality of light-shielding walls each having a triangular crosssection, the light shielding walls being arranged at positions adjacentto the color filters at the pixels where the on-chip lenses are present.

(7) The solid-state imaging device according to (6), in which

each of the light-shielding walls is made of one of a low refractiveindex material having a lower refractive index than the color filtersand a metal material.

(8) The solid-state imaging device according to any one of (1) to (7),in which

each of the color filters at the pixels where the on-chip lenses areabsent has a rectangular cross section.

(9) The solid-state imaging device according to any one of (1) to (8),in which

the lower side is the same in width as the pixels.

(10) The solid-state imaging device according to any one of (1) to (9),in which

each of the color filters is formed on a flattened film.

(11) The solid-state imaging device according to any one of (1) to (10),further including

a plurality of inter-pixel light-shielding films arranged at pixelboundary portions at an interface on the rear surface side of thesemiconductor substrate.

(12) The solid-state imaging device according to (6), further including

a plurality of light-shielding portions embedded between the adjacentphotoelectric conversion portions with a desired depth from the rearsurface side of the semiconductor substrate.

(13) The solid-state imaging device according to (12), in which

the light-shielding walls and the light-shielding portions are connectedto each other at an interface on the rear surface side of thesemiconductor substrate.

(14) The solid-state imaging device according to (12), in which

the light-shielding walls and the light-shielding portions are made of asame material.

(15) The solid-state imaging device according to (12), in which

both side walls of the light-shielding walls held between the colorfilters are slant surfaces.

(16) The solid-state imaging device according to (12), in which

the light-shielding walls are the same in height as the color filters.

(17) The solid-state imaging device according to (12), in which

the light-shielding walls are lower in height than the color filters.

(18) The solid-state imaging device according to (12), in which

each of the light-shielding walls has a trapezoidal cross section.

(19) A method of manufacturing a solid-state imaging device having aplurality of pixels arranged in a matrix pattern, each of the pixelshaving a photoelectric conversion portion configured tophotoelectrically convert light incident from a rear surface side of asemiconductor substrate and a plurality of on-chip lenses arranged forevery other pixel, the on-chip lenses being larger in size than thepixels, the method including

forming each of color filters at the pixels where the on-chip lenses arepresent such that the color filter has a cross-sectional shape whoseupper side close to the on-chip lens is the same in width as the on-chiplens and whose lower side close to the photoelectric conversion portionis shorter than the upper side.

(20) An electronic apparatus, including

a solid-state imaging device having

-   -   a plurality of pixels arranged in a matrix pattern, each of the        pixels having a photoelectric conversion portion configured to        photoelectrically convert light incident from a rear surface        side of a semiconductor substrate, and    -   a plurality of on-chip lenses arranged for every other pixel,        the on-chip lenses being larger in size than the pixels, in        which    -   each of color filters at the pixels where the on-chip lenses are        present has a cross-sectional shape whose upper side close to        the on-chip lens is the same in width as the on-chip lens and        whose lower side close to the photoelectric conversion portion        is shorter than the upper side.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging device comprising: green pixelsincluding a first green pixel and a second green pixel disposeddiagonally in a single line, wherein the first green pixel is disposedbetween a first red pixel and a second red pixel in a horizontaldirection, wherein the second green pixel is disposed between a firstblue pixel and a second blue pixel in the horizontal direction, whereina size of the first blue pixel is smaller than a size of the first greenpixel, and wherein a size of the second blue pixel is smaller than thesize of the first green pixel.
 2. The imaging device of claim 1, whereina shape of the first green pixel is different than a shape of the firstblue pixel.
 3. The imaging device of claim 2, wherein a shape of thefirst green pixel is different than a shape of the second blue pixel. 4.The imaging device of claim 1, wherein a shape of the second green pixelis different than a shape of the first red pixel.
 5. The imaging deviceof claim 4, wherein a shape of the second green pixel is different thana shape of the second red pixel.
 6. The imaging device of claim 1,further comprising: a third green pixel and a fourth green pixeldisposed diagonally along the single line.
 7. The imaging device ofclaim 6, further comprising: a third red pixel and a fourth red pixel,wherein the third green pixel is disposed between the third red pixeland the fourth red pixel.
 8. The imaging device of claim 7, furthercomprising: a third blue pixel and a fourth blue pixel, and wherein thefourth green pixel is disposed between the third blue pixel and thefourth blue pixel.
 9. An electronic apparatus comprising: an imagingdevice including: a plurality of green pixels, including a first greenpixel and a second green pixel disposed diagonally in a single line; aplurality of red pixels, including a first red pixel and a second redpixel; and a plurality of blue pixels, including a first blue pixel anda second blue pixel, wherein the first green pixel is disposed betweenthe first red pixel and the second red pixel in a horizontal direction,wherein the second green pixel is disposed between the first blue pixeland the second blue pixel in the horizontal direction, wherein a size ofthe first blue pixel is smaller than a size of the first green pixel,and wherein a size of the second blue pixel is smaller than the size ofthe first green pixel; a plurality of on-chip lenses; and a digitalsignal processor circuit.
 10. The electronic apparatus of claim 9,wherein a shape of the first green pixel is different than a shape ofthe first blue pixel.
 11. The electronic apparatus of claim 10, whereina shape of the first green pixel is different than a shape of the secondblue pixel.
 12. The electronic apparatus of claim 9, wherein a shape ofthe second green pixel is different than a shape of the red blue pixel.13. The electronic apparatus of claim 12, wherein a shape of the firstgreen pixel is different than a shape of the second red pixel.
 14. Theelectronic apparatus of claim 9, wherein the plurality of green pixelsincludes a third green pixel and a fourth green pixel disposeddiagonally along the single line.
 15. The electronic apparatus of claim14, wherein the plurality of red pixels includes a third red pixel and afourth red pixel, wherein the third green pixel is disposed between thethird red pixel and the fourth red pixel.
 16. The electronic apparatusof claim 15, wherein the plurality of blue pixels includes a third bluepixel and a fourth blue pixel, and wherein the fourth green pixel isdisposed between the third blue pixel and the fourth blue pixel.